Speed Converter
Convert km/h, mph, m/s, knots, Mach and more.
About Speed Units
Speed is distance divided by time. The SI unit is metres per second (m/s). Road speeds use km/h (most countries) or mph (US, UK). Knots (nautical miles per hour) are standard in aviation and maritime. Mach is the ratio of speed to the local speed of sound (~340 m/s at sea level, decreasing at altitude).
Common Conversions
- 1 m/s = 3.6 km/h = 2.237 mph
- 1 km/h = 0.6214 mph
- 1 mph = 1.609 km/h
- 1 knot = 1.852 km/h = 1.151 mph
- Mach 1 ≈ 1,235 km/h at sea level
- Speed of light = 299,792 km/s
Real-World Benchmarks
- Average walking: 5 km/h (3.1 mph)
- Usain Bolt peak: 44.72 km/h (27.8 mph)
- Typical highway: 100–120 km/h
- Commercial airliner: ~900 km/h (Mach 0.85)
- ISS orbit speed: ~27,600 km/h